1. Field of the Invention
The invention relates in general to a displaying device and a method of manufacturing the same, and more particularly to a displaying device with photocurrent-reducing structure and a method of manufacturing the same.
2. Description of the Related Art
Normally, displaying devices such as thin film transistor LCD devices (TFT LCD) are manufactured according to a five-mask manufacturing process. However, during which process, the amorphous silicon (a-Si) layer is photosensitive and is likely to generate photocurrent and cause photocurrent leakage after being exposed to the light.
Referring to FIG. 1, a partial cross-sectional view of a TFT LCD device formed according to a conventional five-mask manufacturing process is shown. The array formed according to a conventional five-mask manufacturing process includes a gate electrode 11 formed by a first metal layer and disposed on a substrate, a gate insulating layer 13 made of silicon nitride, a gate electrode a-Si layer 15, an n+ a-Si layer 16 and a source electrode 17 formed by a second metal layer as shown in FIG. 1. A backlight module is disposed below the substrate to provide the displaying device with a light source. The photosensitivity of a-Si has already been taken into consideration when designing the five-mask manufacturing process of a TFT device, and the pattern of the a-Si layer 15 is designed to be indented into the gate electrode 11. That is, the gate electrode a-Si layer 15 can be completely blocked by the gate electrode 11 to reduce photocurrent leakage. However, part of the light would still be projected onto the gate electrode a-Si layer 15 via a reflection path, causing undesired photocurrent leakage. The reflection path 1 illustrates the reflection of the light between the first metal layer and the second metal layer as shown in arrows of FIG. 1.
In a four-mask manufacturing process, the a-Si layer and the second metal layer are formed in the same layer mask, so the a-Si layer exists under the pattern of the second metal layer. That is, the pattern of the a-Si layer can not be indented in the first metal layer. When the light of the backlight module is projected onto the second metal layer from behind the first metal layer, the light directly is projected onto the a-Si layer, causing even higher photocurrent leakage than the structure manufactured according a five-mask manufacturing process.